import * as vscode from "vscode";

interface GitExtension {
    getAPI(version: number): GitAPI;
}

interface GitAPI {
    repositories: Repository[];
}

interface Repository {
    root: string;
    rootUri: vscode.Uri;
    state: RepositoryState;
    inputBox: { value: string };
    diffWithHEAD(path?: string): Promise<string>;
    diffIndexWithHEAD(path?: string): Promise<string>;
    status(): Promise<void>;
}

interface RepositoryState {
    indexChanges: Change[];
    workingTreeChanges: Change[];
}

interface Change {
    uri: vscode.Uri;
    status: number;
}

export interface GitChange {
    path: string;
    status: "added" | "modified" | "deleted" | "renamed" | "untracked";
    diff?: string;
}

export async function getGitChanges(): Promise<GitChange[]> {
    const repository = await getActiveGitRepository();
    if (!repository) {
        throw new Error("No Git repository found");
    }

    const state = repository.state;
    const changes: GitChange[] = [];

    const stagedChanges = state.indexChanges || [];
    const unstagedChanges = state.workingTreeChanges || [];

    if (stagedChanges.length > 0) {
        for (const change of stagedChanges) {
            changes.push({
                path: change.uri.fsPath,
                status: getChangeStatus(change.status),
            });
        }
    } else if (unstagedChanges.length > 0) {
        const config = vscode.workspace.getConfiguration("aiCommitExt");
        const includeUnstaged = config.get<boolean>("includeUnstaged", false);

        if (includeUnstaged) {
            for (const change of unstagedChanges) {
                changes.push({
                    path: change.uri.fsPath,
                    status: getChangeStatus(change.status),
                });
            }
        }
    }

    return changes;
}

export async function getGitDiff(): Promise<string> {
    const repository = await getActiveGitRepository();
    if (!repository) {
        throw new Error("No Git repository found");
    }

    const state = repository.state;
    let diffOutput = "";

    const stagedChanges = state.indexChanges || [];
    const unstagedChanges = state.workingTreeChanges || [];
    const config = vscode.workspace.getConfiguration("aiCommitExt");
    const includeUnstaged = config.get<boolean>("includeUnstaged", false);

    if (stagedChanges.length > 0) {
        for (const change of stagedChanges) {
            const fileName = change.uri.fsPath.split("/").pop() || "";
            diffOutput += `## ${fileName} (staged)\n`;

            try {
                const diff = await repository.diffIndexWithHEAD(
                    change.uri.fsPath,
                );
                if (diff) {
                    diffOutput += diff + "\n";
                }
            } catch {
                diffOutput += "(Unable to get diff)\n";
            }
        }
    } else if (unstagedChanges.length > 0 && includeUnstaged) {
        for (const change of unstagedChanges) {
            const fileName = change.uri.fsPath.split("/").pop() || "";
            diffOutput += `## ${fileName} (unstaged)\n`;

            try {
                const diff = await repository.diffWithHEAD(change.uri.fsPath);
                if (diff) {
                    diffOutput += diff + "\n";
                }
            } catch {
                diffOutput += "(Unable to get diff)\n";
            }
        }
    }

    if (!diffOutput) {
        throw new Error("No changes to commit");
    }

    return diffOutput;
}

async function getActiveGitRepository(): Promise<Repository | null> {
    const gitExtension =
        vscode.extensions.getExtension<GitExtension>("vscode.git");
    if (!gitExtension) {
        throw new Error("Git extension not found");
    }

    const api = gitExtension.exports.getAPI(1);
    if (api.repositories.length === 0) {
        return null;
    }
    return api.repositories[0];
}

function getChangeStatus(status: number): GitChange["status"] {
    const Status = {
        INDEX_MODIFIED: 0,
        INDEX_ADDED: 1,
        INDEX_DELETED: 2,
        INDEX_RENAMED: 3,
        MODIFIED: 4,
        DELETED: 5,
        UNTRACKED: 6,
    };

    if (status === Status.INDEX_ADDED || status === Status.UNTRACKED) {
        return "added";
    }
    if (status === Status.INDEX_DELETED || status === Status.DELETED) {
        return "deleted";
    }
    if (status === Status.INDEX_RENAMED) {
        return "renamed";
    }

    return "modified";
}

export async function getRepositoryRoot(): Promise<string | null> {
    const repository = await getActiveGitRepository();
    if (!repository) {
        return null;
    }
    if (typeof repository.root === "string") {
        return repository.root;
    }
    return repository.rootUri.fsPath;
}